JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<div id="circle"></div>

CSS

body {
  height: 1000px;
}
#circle {
  position: absolute;
  width: 20px;
  height: 20px;
  background: #000;
  border-radius: 100%;
  opacity: 0.5;
  top: -10px;
  left: -10px;
  webkit-transition: all 0.1s ease;
  -moz-transition: all 0.1s ease;
  -ms-transition: all 0.1s ease;
  -o-transition: all 0.1s ease;
  transition: all 0.1s ease;
}

JavaScript

setTimeout(function() {
	$('body').mousemove(function(e){
    $('#circle').css({'top': e.clientY+$(window).scrollTop(), 'left': e.clientX});
  });
});