Tampermonkey.js

// ==UserScript==
// @name         Get div contents and print it to console on OAM course
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        http://www.myatoma.com/Simulatore/*
// @require https://code.jquery.com/jquery-2.2.4.min.js
// ==/UserScript==

var $ = window.jQuery;
$( document ).ready(function() {
    console.log("Sono pronto :-)");
});

//More Details https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver
// select the target node
var target = document.querySelector('#sim_domanda')
// create an observer instance
var observer = new MutationObserver(function(mutations) {

    console.log($('#sim_domanda').text());
  //Questa cosa non funziona
    $.post("https://www.jsonstore.io/fb01957e5fe8a916d2fce4ab5f2a2b2c64e3d033b8192da25c07d509c0fc1965",
           {
        "Domanda" : $('#sim_domanda').text()
    });

});
// configuration of the observer:
var config = { attributes: true, childList: true, characterData: true };
// pass in the target node, as well as the observer options
observer.observe(target, config);