I will offer you a different example which I hope is similar to what you're asking.
My form includes a combo named cboNames. This is the query for its row source:
SELECT f.id, f.fname, f.date_added
FROM food_test AS f
ORDER BY f.fname, f.date_added;
In the combo's After Update event I can access the values of those 3 columns in the selected combo row by referring to the Column index. Notice the column index numbering starts with zero.
Private Sub cboNames_AfterUpdate()
Debug.Print Me.cboNames.Column(0)
Debug.Print Me.cboNames.Column(1)
Debug.Print Me.cboNames.Column(2)
End Sub
So if I wanted to put the date_added value into another data control, I could add this to the combo's After Update event.
Me.SomeOtherControl = Me.cboNames.Colummn(2)
However I wouldn't actually store both id and date_added in a row of another table. In my food table, each id is associated with a unique combination of fname and date_added. So I would store only the id, and use a SELECT with a JOIN to the food table to look up the associated fname and date_added values whenever I needed them.