If your combobox has one or more columns hidden, upon leaving the combobox, only the column(s) you don't have hidden will be displayed.
If, on the other hand, you need/want to hide one of the columns you can show the other column in a text box. For example, if you are displaying the LastName in the combobox (column(0)), then set the control source property of the text box equal to =cboName.column(1)