Private Sub Worksheet_Change(ByVal Target As Range)
    On Error Resume Next
    For Each c In Target
        With c
            .AddComment
            .Comment.Text Text:="" & Now
        End With
    Next
End Sub

如需要在j4:p5000范围内单元格中实现此功能，则改成：

Private Sub Worksheet_Change(ByVal Target As Range)
    On Error Resume Next
    For Each c In Target
        If c.Column > 9 And c.Column < 17 And c.Row > 3 And c.Row < 5001 Then
        With c
            .AddComment
            .Comment.Text Text:="" & Now
        End With
        End If
    Next
End Sub