What are the Constructs for ~Receiving~ Asynchronous Callback Delegate(?)/Function Ptr(?) data in a DLL/API Written in VB.Net;

I need to know the VB.NET language constructs (example code would be appreciated) to use in an DLL that will emulate a 3rd Party API.  (I'm writting an App that interfaces with the API and need to write my own DLL/API to test certain scenarios that I can't simulate with the 3rd party API).  The 3rd Party API is written in C++ or Delphi(?) and I have successfully written code in my App to interface with it.

I ~DO NOT NEED~ information as to how to interface with the API.

I ~DO NEED~ to know how to accept delegate(?) / function pointer(?) data in my DLL/API emulator and then use that captured delegate(?)/function pointer(?) data in the DLL/API emulator to make 'event-type' calls back to my app and to the delegate(?) callback functions therein, asynchronously.

Thanks!!