How to add some static data to Datepicker date?

How to add some static data to Datepicker date?

For a jQuery UI's datepicker field and I'd like to add a static timestamp to a selected date value upon date selection.  I've looked at all the attributes for datepicker, however, none seems appropriate for this need.
And I attempted to trigger onblur and onMouseout respectively to call up a function to append the static timestamp, however, it quickly shows up and then disappear.  So, what to do this?  And I wonder if there's a special event, which essentially kicks off after all other events are done... 

Thanks in advance.