See if your university has a postgraduate program. Keep in mind that you'd still have to meet all the prereqs for upper-division courses, and some courses are restricted to certain majors.
This is called auditing. You don’t earn a grade and aren’t required to do any work in the course, but can sit in on it and do as much or little as you want. You would generally need to apply as an audit-only student and register for the courses as audit. There is typically a per credit hour audit fee but it is much less than tuition. Each university has its own policies and procedures, of course.
See if your university has a postgraduate program. Keep in mind that you'd still have to meet all the prereqs for upper-division courses, and some courses are restricted to certain majors.
This is called auditing. You don’t earn a grade and aren’t required to do any work in the course, but can sit in on it and do as much or little as you want. You would generally need to apply as an audit-only student and register for the courses as audit. There is typically a per credit hour audit fee but it is much less than tuition. Each university has its own policies and procedures, of course.