flie modification date

Hi, I hope someone can help me with this.
Is there any function that tells me if a cell in my complete file has been modified?
If theres a function that does that, then I want to return the date of modification in another cell:
If file was modificated then please tell me today's date, if it wasn't modified then dont modify this cell.
Another thing is that I would rather this function not to be a macro, since a lot of people will be using this file and I dont want excel to ask everybody if they want to run macros.
thanks in advance