Private Declare Function GetLastInputInfo Lib "user32.dll" (ByRef plii As LASTINPUTINFO) As Long

Private Type LASTINPUTINFO
    cbSize As Long
    dwTime As Long
End Type

Private Sub Timer1_Timer()
    Dim LII As LASTINPUTINFO
    
    LII.cbSize = Len(LII)
    LII.dwTime = 0
    
    Call GetLastInputInfo(LII)
  
    Text1.Text = LII.dwTime
End Sub