Layer functionality onto the draggable using the start, drag, and stop events. Start is fired at the start of the drag; drag during the drag; and stop when dragging stops.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>jQuery UI Draggable - Events</title>
  <link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css">
  <link rel="stylesheet" href="/resources/demos/style.css">
  <style>
  #draggable { width: 16em; padding: 0 1em; }
  #draggable ul li { margin: 1em 0; padding: 0.5em 0; } * html #draggable ul li { height: 1%; }
  #draggable ul li span.ui-icon { float: left; }
  #draggable ul li span.count { font-weight: bold; }
  </style>
  <script src="https://code.jquery.com/jquery-1.12.4.js"></script>
  <script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
  <script>
  $( function() {
    var $start_counter = $( "#event-start" ),
      $drag_counter = $( "#event-drag" ),
      $stop_counter = $( "#event-stop" ),
      counts = [ 0, 0, 0 ];
 
    $( "#draggable" ).draggable({
      start: function() {
        counts[ 0 ]++;
        updateCounterStatus( $start_counter, counts[ 0 ] );
      },
      drag: function() {
        counts[ 1 ]++;
        updateCounterStatus( $drag_counter, counts[ 1 ] );
      },
      stop: function() {
        counts[ 2 ]++;
        updateCounterStatus( $stop_counter, counts[ 2 ] );
      }
    });
 
    function updateCounterStatus( $event_counter, new_count ) {
      // first update the status visually...
      if ( !$event_counter.hasClass( "ui-state-hover" ) ) {
        $event_counter.addClass( "ui-state-hover" )
          .siblings().removeClass( "ui-state-hover" );
      }
      // ...then update the numbers
      $( "span.count", $event_counter ).text( new_count );
    }
  } );
  </script>
</head>
<body>
 
<div id="draggable" class="ui-widget ui-widget-content">
 
  <p>Drag me to trigger the chain of events.</p>
 
  <ul class="ui-helper-reset">
    <li id="event-start" class="ui-state-default ui-corner-all"><span class="ui-icon ui-icon-play"></span>&quot;start&quot; invoked <span class="count">0</span>x</li>
    <li id="event-drag" class="ui-state-default ui-corner-all"><span class="ui-icon ui-icon-arrow-4"></span>&quot;drag&quot; invoked <span class="count">0</span>x</li>
    <li id="event-stop" class="ui-state-default ui-corner-all"><span class="ui-icon ui-icon-stop"></span>&quot;stop&quot; invoked <span class="count">0</span>x</li>
  </ul>
</div>
 
 
</body>
</html>


output