I’m not sure exactly what implementation of iClass you’re referencing (as there’s a few different types), but if you’re talking about the 13.56mhz fobs… they can range from trivial (1 hour of learning and $35-100 in equipment) to impossible.

(I do realize that equipment cost may be prohibitive where you are located).

But, there are attack techniques - especially if people wear these / store them in a pocket or attached to a belt, that can sometimes compromise and copy them. It might not be an innocent accidental bump in that line for coffee!

Here’s a basic walkthrough for one type.

https://www.minifob.com/how-to-guides/how-to-actually-copy-y...