Drag and drop the current date field which is under.Object Library > Custom > Current Date.
Select the field In the Binding change the Date Fomat to Time.If you want to change the pattern Object > Field > Pattern > Locale Select English(USA) and select what ever pattern you want.
Then modify the script of the same field as below.
$.rawValue = num2time(time(), "HH:MM:SS") Language should be formcalc.
Thanks
Vjay