From your screenshot the fields are on the same form so you don't need DLookup.
In the After Update event of the combo box:

TextboxName = ComboBoxName.Column(3)

This will give you the value of the 4th column (I'm assuming you have a hidden column (an ID)).

EFA I HAVE TAKEN FROM TABLE FM AND I WANT THE VALUE OF FITTINGS TO DISPLAY IN EFAP LABEL AS PER THE ITEMS WHICH I SELECT.