Edit in JSFiddle 
<!doctype html>
<html lang="en">
    <head>
        <link rel="stylesheet" href="https://tiles.locationiq.com/v3/libs/openlayers/8.2.0/ol.css" type="text/css">
        <script src="https://tiles.locationiq.com/v3/libs/openlayers/8.2.0/ol.js"></script>
        <style>
            body { margin:0px; padding:0px; }
            #map { position:absolute; top:0px; bottom:0px; width:100%; }
        </style>
        <script src="https://tiles.locationiq.com/v3/libs/olms/12.0.0/olms.js" type="text/javascript"></script>
        <title>Draggable Marker</title>
    </head>
    <body>
        <style>
            .marker {
                display: block;
                border: none;
                cursor: pointer;
                padding: 0;
            }

            .coordinates {
                background: rgba(0, 0, 0, 0.7);
                color: #fff;
                position: absolute;
                bottom: 40px;
                left: 10px;
                padding: 5px 10px;
                margin: 0;
                font-size: 14px;
                line-height: 18px;
                border-radius: 3px;
                display: none;
            }
            
        </style>
        <div id="map"></div>
        <pre id="coordinates" class="coordinates"></pre>
        <script type="text/javascript">
            var coordinates = document.getElementById('coordinates');

            var key = 'pk.aa7f5d0539c5675b7f3429402939d8fa';   //Insert your LocationIQ access token here

            var styleJson = 'https://tiles-staging.locationiq.com/v3/streets/vector.json?key=' + key;

            const map = new ol.Map({
                target: 'map',
                view: new ol.View({
                    center: ol.proj.fromLonLat([-122.42, 37.779]),
                    zoom: 12
                })
            });


            //to create a marker
            var marker1 = new ol.Feature({
                    geometry: new ol.geom.Point(
                    ol.proj.fromLonLat([-122.444733, 37.767443])
                ), 
            });

            //to enhance style and add icon to the map
            marker1.setStyle(new ol.style.Style({
                image: new ol.style.Icon({ 
                    scale: 0.5,               //scale to adjust the proportion of the icon   
                    src: 'https://tiles.locationiq.com/static/images/marker.png',           //link of the icon
                })
            }));

            //Let’s include the markers and create a vector source with it
            var vectorSource = new ol.source.Vector({
                features: [marker1]          
            });

            //Let’s create a vector layer, with a source created above
            var vectorLayer = new ol.layer.Vector({
                source: vectorSource,
                zIndex: 1
            });

            map.addLayer(vectorLayer);

            var translate1 = new ol.interaction.Translate({
                features: new ol.Collection([marker1])
            });
            
            map.addInteraction(translate1);

            // After the mouse is released the following function is executed which updates the displayed lat and long
            translate1.on('translateend', function(e) {
                if (e.dragging) return;
                var coordinate = e.coordinate;
                var lngLat = ol.proj.toLonLat(coordinate);
                coordinates.style.display = 'block';
                coordinates.innerHTML = 'Latitude: ' + lngLat[1] + '<br />Longitude: ' + lngLat[0];
            });
            olms.apply(map, styleJson);
        </script>
    </body>
</html>