I did see that it was a system level event, but I couldn't gauge from the question whether the key point of your question was re: the MouseMove event or that it was to be a system-wide event... I erred in favour of what I presumed was the most likely (my apologies). The short answer is, as far as I'm aware, there's no easy way to integrate .NET namespaces into VBA code. There may, however, be a workaround...
Like what you've referenced here, I'm also looking to leverage one of the .NET Namespaces in a project of mine (Windows.Media.OCR), and some super smart people in the AutoHotkey community have managed to do it. My default position is that if you can do it in Autohotkey, then you can do it in VBA because both languages would be using the same Win32 API method. That said, that approach isn't extremely straight forward.
Using just Win32 APIs, though, you could possibly detect mousemovement events anywhere on the screen (ie., not over ActiveX or userform/UF controls) with the GetCursorPos API. This returns the X/Y coordinates of the mouse anywhere on the screen. Using some kind of timer, you could use this APi to get the mouse cursor position on every tick and then test to see whether or not the coordinates matches the coordinates previous recorded. If they don't match then the mouse has moved.
Alternatively, you could possibly use another API to hook into the Mouse, but I would need to look into that a little bit more.
The point is - detecting any mouse movement is doable, but there may be an even simpler solution than the above depending on your specific need/use case.
