This did get me thinking from a computer security perspective: I guess in theory you could do stuff like using unicode special characters in place of the alphabet, putting invisible unicode control characters between each letter, or making a custom font that makes non-letter characters look like letters, but at that point why are you not just spending your effort actually writing your own paper? And it’s also likely that Turnitin would be able to detect that and if not check the paper, at least alert the professor that something is up.

Cheating on an academic work is such a sleazy thing to do that if you feel the need to do it, you shouldn’t be in academia.