When you take a noncredit college course (also called auditing), you may not be able to get a traditional student loan. Most federally backed loans are given only to students enrolled full time, and if you're auditing courses, you aren't considered a full-time student. However, there are ways to acquire private loans and other sources of funding for auditing a college course. One major educational lender does offer continuing education loans; you can also check with your bank and/or employer for assistance.
Check out the Sallie Mae Continuing Education Loan Program. This loan is available to students who are "pursuing career training while they work, taking time to learn a new skill or just beginning to train for a new career," according to Sallie Mae's website. Aid for noncredit courses is available. Borrowers are subject to a credit check, and loans may require a cosigner.
Ask your bank or credit union about private loans for educational purposes. The interest rate may be higher and the repayment schedule more stringent, but if you have good credit, you may be able to obtain a loan for your courses in the same way you'd obtain one for a mortgage or car.
Ask your employer if it offers reimbursement for college classes. The reimbursement may be contingent on many factors, including your grade in the course (students auditing a course don't get graded) and whether the subject matter relates to your current job, but you never know what might be available. If you work for a nonprofit organization, there might be grant money available to take the course if it relates to your organization's mission/goals.
Beware of "student loan" offers from shady companies that don't require you to do a complete application and/or credit check. The only legitimate sources of student aid are the Department of Education and FDIC- or NCUA-backed banks and credit unions.