Edit in JSFiddle 
<!DOCTYPE html>
<html>

    <head>
        <meta charset="utf-8" />
        <title>Draggable Marker</title>
        <meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
        
        <script src='https://tiles.locationiq.com/v3/libs/maplibre-gl/1.15.2/maplibre-gl.js'></script>
        <link href='https://tiles.locationiq.com/v3/libs/maplibre-gl/1.15.2/maplibre-gl.css' rel='stylesheet' />
        
        <script src='https://tiles.locationiq.com/v3/js/liq-styles-ctrl-libre-gl.js?v=0.1.8'></script>
        <link href='https://tiles.locationiq.com/v3/css/liq-styles-ctrl-libre-gl.css?v=0.1.8' rel="stylesheet" />

        <style>
            body {
                margin: 0;
                padding: 0;
            }

            #map {
                position: absolute;
                top: 0;
                bottom: 0;
                width: 100%;
            }
        </style>
    </head>

    <body>
        <style>
            .marker {
                display: block;
                border: none;
                cursor: pointer;
                padding: 0;
                width: 50px;
                height: 50px;

            }

            .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>
            
            //Add your LocationIQ Maps Access Token here (not the API token!)
            locationiq.key = 'pk.aa7f5d0539c5675b7f3429402939d8fa';
            //Define the map and configure the map's theme
            var map = new maplibregl.Map({
                container: 'map',
                style: locationiq.getLayer("Streets"),
                zoom: 12,
                center: [-122.42, 37.779]
            });

            var coordinates = document.getElementById('coordinates');
                
            // First create DOM element for the marker
            var el = document.createElement('div');
            el.className = 'marker';
            el.id = 'marker';
            // Set marker properties using JS
            el.style.backgroundImage = 'url(https://tiles.locationiq.com/static/images/marker50px.png)';

            var marker = new maplibregl.Marker(el, {
                draggable: true
            }).setLngLat([-122.444733, 37.767443])
            .addTo(map);

            // After the mouse is released the following function is executed which updates the displayed lat and long
            function onDragEnd() {
                var lngLat = marker.getLngLat();
                coordinates.style.display = 'block';
                coordinates.innerHTML =
                    'Latitude: ' + lngLat.lat + '<br />Longitude: ' + lngLat.lng;
            }

            marker.on('dragend', onDragEnd);
            
        </script>
    </body>
</html>