Option Explicit

Private mblnMyStop As Boolean

Private Sub Class_Initialize()
    mblnMyStop = False
End Sub

Public Sub DoMyMethod()

    While Not mblnMyStop
        DoEvents
        'Здесь будет ваш код  (код из вашей функции или процедуры):
        Form1.Caption = Time
    Wend
    
End Sub

Public Property Get MyStop() As Boolean
     MyStop = mblnMyStop
End Property

Public Property Let MyStop(ByVal vNewValue As Boolean)
    mblnMyStop = vNewValue
End Property

Option Explicit

Private mobjMyClass As New Class1

Private Sub Command1_Click()
    mobjMyClass.DoMyMethod
End Sub

Private Sub Command2_Click()
   mobjMyClass.MyStop = Not mobjMyClass.MyStop
End Sub