adding few more points here.
if you fill some values and save the form then there is ootb ui action "Show History". click on that and it will show you the old and new values changes on your form. that's actually coming from sys_history_line table.
but i am not sure in real production system the data would be huge so it will definitely take alot of time to give you some output. or may be it will give transaction time out.
