Here is a procedure may help you
Private Sub Form_Load()
Dim g_DBINFO as ADODB.Connection
Set g_DBINFO= New ADODB.Connection
g_DBINFO.ConnectionString = "Provider=Microsoft.Jet.OLEDB.3.51;Persist Security Info=False;Data Source=" & App.path & "\Data\dbinfo.mdb"
g_DBINFO.CursorLocation = adUseClient
g_DBINFO.Open
LoadListDB cboControl,g_DBINFO,"SELECT field_name FROM table_name"
end sub

Public Sub LoadListDB(cbo As ComboBox, dbc As ADODB.Connection, ByVal sm_SQL As String)
Dim rs As ADODB.Recordset
Set rs = New ADODB.Recordset
rs.Open sm_SQL, dbc, adOpenStatic, adLockReadOnly
cbo.Clear
Do Until rs.EOF
Select Case rs.Fields.count
Case 1

      cbo.AddItem rs.Fields(0).Value
      cbo.itemData(cbo.NewIndex) = rs.Fields(0).Value
    Case Else
      If IsNull(rs.Fields(1).Value) Then
       cbo.AddItem CStr(rs.Fields(0).Value) + " - "
       cbo.itemData(cbo.NewIndex) = rs.Fields(0).Value
      Else
       cbo.AddItem CStr(rs.Fields(0).Value) + " - " + rs.Fields(1).Value
       cbo.itemData(cbo.NewIndex) = rs.Fields(0).Value
      End If

End Select
rs.MoveNext
Loop
rs.Close
Set rs = Nothing
End Sub