FocusClickTab

Option Explicit
Dim Mouse As Boolean
Private Sub Form_Load()
Mouse = False
End Sub

Private Sub Text1_GotFocus()
If Mouse = True Then
Call MsgBox("Hai cliccato con il mouse")
Else
Call MsgBox("Hai premuto tab")
End If
Mouse = False
End Sub

Private Sub Text1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
Mouse = True
End Sub

'----------------------------------------------------------------

Sapere se un controllo ha ricevuto il focus

In Form metti una textbox ed un altro controllo
(es.CommandButton):