I think its best you refer to this thread talking about how Exploiting works and what you can do to prevent it: Exploiting Explained
To answer your question, its practically “impossible” to detect people who use exploits in any case scenario. However, you can try to [stop speed exploits]How to Prevent Speed Hacking - #5 by AllYourBlox) and “Godding” through sanity checks.
People learn the how the actual exploit works itself before patching in some cases.
FE (Filtering Enabled) is essentially a wall which stops unauthorised changes on the server, Remote events are used. You need to use events such as RemoteEvents to make these changes and check if the change isn’t exploitable in a way that someone can abuse it.
I believe its best you get to know what Filtering Enabled is so you can understand how Sanity checks come into play:
Just remember, the more checks you have when you’re using events, typically the more secure and robust it is against exploiters!