What i am asking is if i remove the table field in Control source and add a expression to it. How can i submit that value to table.
You are asking about using an unbound field but storing the result. Yes, this is possible but doing this is making more work for yourself and it also avoids the primary strength of Access - to automatically store items bound to a form.
I believe there is a misunderstanding here, but I haven't identified its nature yet. So... let's say that you want this. OK, acknowledged, it is what you want and I assure you it is possible. But WHY do you want to do it this particular way, which we see as unusual?
What we see is this: You could leave this as a field bound to a control and simply enter a new, different value in that control. That new value would be saved with the rest of the record when you save the form's current record anyway.
You want to do something other than the normal Access style of doing things, so you must have a reason as to WHY you wish to do it this way. Can you explain that reason to us? Because right now we don't see why you want to go out of your way to do something that Access normally does anyway.