Depends on how you are storing it in Access I guess.

Use the Selected property to see if the item was selected. Add a listbox, commandbutton, and set the multiselect option in the listbox to test this code.

Private Sub UserForm_Initialize()
  ListBox1.List = Array(1, 2, 3, 4, 5)
End Sub

Private Sub CommandButton1_Click()
  Dim i As Integer
  For i = 0 To ListBox1.ListCount - 1
    Debug.Print i, ListBox1.List(i), ListBox1.Selected(i)
  Next i
  Unload Me
End Sub