I actually had my first encounter last week with a student using ChatGPT to write assigned essays.
Quite frankly, I noticed that the essays were 'too good'. When confronted, the student initially denied using any generative-text tools, but has since come clean.
As I stated in a post about ChatGPT several weeks ago, educators are going to have to abandon essays as a means of measuring student engagement and comprehension (unless the essays are written 'by hand' or proctored).