First recorded usage of “Hacker” from MIT paper in 1963

"Hack" related to writing has been around much longer. IIRC, Byron described himself this way. The article here concerns the tech sense only.

Also, in the case of a writer the noun isn't "hacker" but just "hack".

Edit: can't find the reference in Byron. I am reminded, though, that a "hack" used to refer to an old or low-quality horse that would be let out for hire. Perhaps it got applied to writers from there.