One of the unofficial solutions used in Warcraft 3 was to spawn an illegal 3D model object in the corner of the map by a trigger as soon as the map begins, or during random spot checks during the map gameplay.
The model would crash the game (and world editor, that's why we have to spawn it during runtime) when displayed, but it wouldn't get displayed when under fog of war, so you'd put it in a place that is impossible to be seen by a player under normal circumstances. But if someone uses a fog of war cheat or a maphack, it'd crash for them.
Of course it won't prevent you from more advanced hacks which e.g. modify the client and display an overlay of the enemy units rather than just revealing the fog of war.
Similarly, a common technique used within notably the DotA community (of which's map didn't have such a tripwire) was to analyze the replay for what were termed "fog clicks", since for whatever reason object selection is part of the command stream and those using maphack would often, intentionally or inadvertently, select objects otherwise under fog.
That's cool. AoE2 scenarios sometimes had a different kind of anti-cheat, preventing players from deleting buildings that would otherwise count as points to enemies who raze them. That relied on a lot of complex triggers that I think involved spawning birds to keep count of things.
The model would crash the game (and world editor, that's why we have to spawn it during runtime) when displayed, but it wouldn't get displayed when under fog of war, so you'd put it in a place that is impossible to be seen by a player under normal circumstances. But if someone uses a fog of war cheat or a maphack, it'd crash for them.
Of course it won't prevent you from more advanced hacks which e.g. modify the client and display an overlay of the enemy units rather than just revealing the fog of war.