In the sleazy shadows, where cheaters and phonies dwell, if you’re planning to hire somebody to help you cheat your way to your degree, with their “assistance.”
You have a advisor, a respected faculty member. Maybe you’re not a cheat. Maybe you’re disabled — perhaps blind or unable to type or dictate or both. Of course a good university will make “reasonable accommodations,” help you actually need.
Ask your advisor this question, and if it’s genuinely legitimate you can get the help you need.
PS: In my department it was considered OK, even a good idea, to hire a dissertation consultant (often a student from another department) to assist with complex statistical issues. They were like tutors, and certainly didn’t write anything for doctoral candidates, but were part of the learning process, and their involvement was never a secret.