Tips & Tricks: ArcmapSpy on GitHub
Download ArcmapSpy and look into ArcObjects.
ArcmapSpy is an AddIn for the Esri ArcMap software and provides insight into the internals of ArcObjects.
It consists of several tools which are accessible from a stand-alone toolbar. Watch the video to see how it works!
Find further information about ArcmapSpy as well as the download on GitHub.