I have experience in this area. Professional espionage agents use what is called a "Surveillance Detection Route" (SDR) to determine if someone is monitoring their movements. I mention this because in the case of espionage, being followed is a case of national security and can be a matter of life and death, so you can be sure it is the go-to method to avoid detection.
Essentially it involves making a few stops along a predetermined route in order to assess if you are being followed. For example, if you are driving home from work, you could make planned stops at the dry cleaner to pick up your laundry, a restaurant to pick up your dinner, and a drug store to shop around a few minutes. At each place, you freeze the action for a moment and note who is around you in the parking lot, the store, the area, etc. You can sit in your car a moment and take note of any other cars that pull in at the same time or stop around you, or anyone who follows you into a store or seems to be sitting in the parking lot with no discernible purpose other than following you. If you notice the same car or person twice during your entire SDR, you are definitely being followed. Since you are going about regular, everyday events, it arouses no credible suspicion in anyone following you. That is, it's a solid way to determine if anyone is following you without looking suspicious or being confrontational yourself.
Also, you should stop being predictable in your movements. Start varying your routes and your times so you are not predictable with where you are and when you'll be there.
Now, not knowing the full back story of your father and what he's capable of, I wouldn't know what to advise for further action if you determine you are indeed being followed. That is, whether or not you should confront your follower, take pictures or video of them, notify local law enforcement, etc. would depend on the circumstances. Feel free to PM me if you'd like more advice. Without knowing more, my default advice would be to write down in a journal anyone you notice following you. Note the date, time, their appearance, where you were, their car's make/model/color/license/etc., and any other info you can gather. If you can safely and surreptitiously take a picture or video with your phone, that would be excellent evidence to provide a solid case for stalking. Once you've established any kind of pattern with being followed, the police should not be dismissive of you.
Also, I've written a book on the subject of personal protection in case you'd like to get it. It's called "Get Off The X" by Scott Richardson (a pseudonym) and I wrote it specifically to address situations like yours, with advice for protecting yourself in all kinds of situations at home and when out and about. You can find it on Amazon, IBooks, etc.
