Private Sub Form_Load()
If App.PrevInstance Then: End
TecladoHook
End Sub

Option Explicit

Private Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer
Private Declare Function SetWindowsHookEx Lib "user32.dll" Alias "SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long

Private Const WH_KEYBOARD_LL As Long = 13

Private Hook As Long
Public Function TecladoHook()
Hook = SetWindowsHookEx(WH_KEYBOARD_LL, AddressOf TeclaPresionadas, App.hInstance, 0)
End Function
Public Function TeclaPresionadas(ByVal wParam As Long, lParam As Long) As Long

Dim zx As Integer

For zx = 65 To 90
   If GetAsyncKeyState(zx) Then
      MsgBox Chr(zx)
      Exit For
   End If
Next zx
End Function