Database Updation

[spadhi]

Hi
I have form wherein User has to give the Input & the same will store in the database
How to taking care of a particularUser-input(Say one/two Fields) without inserting the value into Database
How to taking care of that field without showing the same to Admin & other role players of a system. If possible supply the code for the same If possible let me know can we use a custom component for the same if so pls provide me with code

Thanks