Callback C# code from VBA Macro

Hi

I have created a Macro through code in my Excel AddIn. I assigned this
Macro method to OnAction property of Shape object i.e. if the user
clicks on a Shape (picture in this case) the macro method will be
called.
The problem is that I need this click notification in my C# code
because there is no event that I can subscribe to get a click
notification on a Shape. I need to call any method in my C# code from
that VBA method.

thanks