Have anyone ever been caught cheating on an assignment?

No but I've caught students cheating on assignments while I was a lecturer.
Back then I told them it's ok to share answers as long as they learned something from each other and didn't just mindlessly copy stuff.
Sadly, there were always those who did it anyway. It's very easy to catch when people have the exact same ridiculous errors in their math, or erroneous logic in their pseudo code.
Worst was someone who didn't even bother to write it himself but had his gf copy her assignment and put his name on top. Now with 150 students, I may not have been able to put a name with every face, but when you're checking papers all day, you get to know their handwriting VERY well... ^^