<div id="header"></div>
<style>
    #header {
    	height: 200px;
        background-image: url('https://i.postimg.cc/BbRm96cn/daniel-mirlea-u5-Qzs-Kvu7-YA-unsplash.jpg');
    }
</style>

<script>
    document.addEventListener('mousemove', function (event) {
      if (window.event) { // IE fix
          event = window.event;
      }
    
      // Grab the mouse's X-position.
      var mousex = event.clientX;
      var mousey = event.clientY;
      var header = document.getElementById('header');
      header.style.backgroundPosition = '-' + mousex/3 + 'px -' + mousey/2 + 'px';
    }, false);
    
</script>