Public Class myUC
    Public Event ButtonClicked()
 
    Public ReadOnly Property CustomText() As String
        Get
            Return TextBox1.Text
        End Get
    End Property
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        RaiseEvent ButtonClicked()
    End Sub
End Class

Public Class Form1
    Private WithEvents myControl As New myUC
    Private mTestString As String = ""
 
    Public Sub New()
        InitializeComponent()
        Me.Controls.Add(myControl)
    End Sub
 
    Private Sub myControl_ButtonClicked() Handles myControl.ButtonClicked
        Aktion()
    End Sub
 
    Private Sub Aktion()
        mTestString = myControl.CustomText
        Debug.WriteLine(mTestString)
        Me.WindowState = FormWindowState.Minimized
    End Sub
End Class