If its a TextBox then set a flag in the text changed event;
Code:
    Dim SomethingHasChanged As Boolean = False
    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) _
    Handles TextBox1.TextChanged
        SomethingHasChanged = True
    End Sub
The principle is the same for Radiobuttons and Checkboxes.