Dim DGVCB As DataGridViewCheckBoxColumn = New DataGridViewCheckBoxColumn()
    With DGVCB
      .ValueType = GetType(Boolean)
      .HeaderText = "Auswahl"
      .Name = "Auswahl"
      .DisplayIndex = 0
    End With
    DGV.Columns.Add(DGVCB)

MsgBox(DGV.SelectedCells.Item(0).Value)

DGV.SelectedCells.Item(0).Value.ToString

Dim DGVCB As DataGridViewCheckBoxColumn = New DataGridViewCheckBoxColumn()
With DGVCB
            .ValueType = GetType(Boolean)
            .HeaderText = "Auswahl"
            .Name = "Auswahl"
            .DisplayIndex = 0
End With
DataGridView1.Columns.Add(DGVCB)
DataGridView1.Rows.Add("true")
DataGridView1.Rows.Add("false")
 
Private Sub DataGridView1_CellContentClick _
         (ByVal sender As System.Object, _
         ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) _
         Handles DataGridView1.CellContentClick
 
    If e.ColumnIndex = 0 Then
       Dim str As String = _
       DataGridView1.Rows(e.RowIndex).Cells(0).Value.ToString
       MsgBox("In Zeile: " & CStr(e.RowIndex) & " stand: " & str)
    End If
End Sub

Private Sub DGV_CellContentClick(ByVal sender As System.Object, _
                                 ByVal e As _
                                 System.Windows.Forms.DataGridViewCellEventArgs_
                                 ) _
                                 Handles DGV.CellContentClick
    Me.DGV.EndEdit()'die bearbeitung muss erstmal abgeschlossen werden
    Try
      MsgBox(DGV.SelectedCells.Item(0).RowIndex.ToString & ";" & _
             DGV.SelectedCells.Item(0).ColumnIndex.ToString & ";" & _
             DGV.SelectedCells.Item(0).Value.ToString)
    Catch ex As Exception
      MsgBox(ex.Message)
    End Try
 
  End Sub