College courses are extremely expensive, you have to battle to sign up for them…..yet unlike other expensive stuff, no one guards the classes.
I was recommended by someone to take a graduate level management course taught by an extremely prestigious professor who has “been there, done that” in the business world.
Instead of signing up for this class, I just looked up the publicly available class time/location and started going! I told the professor I was not paying for the class, nor was I any longer a student, and he happily agreed to add me to the class. I imagine some professors would PREFER students who WANT to take the class over those taking it as a requirement.
When I was a student I used to sit in on classes where they would talk about subjects I needed more knowledge on (Particularly computer science classes where I wanted to know how something was created). The best part is you can go speak with the professor after class or in their office hours, and they are always more than happy to speak with you.
I never fully realized it when I was a student….but the university is one of the few places where you have world-class authorities on a subject, and you can access all their expertise free of charge.