How to add a callback on click jQuery function?

I have an asynchronous problem and for solve it I think I must use a callback. I want to execute some code after the code that is inside of the click() function finishes. How can I do that?

$("#mybutton").click(function() {
    $.ajax({
      type: 'GET',
      data: {
        accion: "get_option_child",
        id: id
      },
      url: 'webservices.php',
      success: function(data) {
        var json = JSON.parse(data);
        // some code
      }
  });
});

Just add a call to your desired function at the end of the success handler for ajax:

$("#agregar_opcion").click(function() {
  // ...
  $.ajax({
    // ...
    success: function(data) {
      // ...
      functionThatRunsAfterAjaxSuccess();
    }
  });
});

function functionThatRunsAfterAjaxSuccess() {
  // gets called once the ajax call happening on click is successful
}