You can track offline marketing various ways. If you're wanting people to call a phone number that's in your ad, you can get a phone number from Google (or any number of places) and track how many calls you get. At one point I had several toll-free numbers that I used in my marketing. I can't remember the name of the company I got them from - it's been awhile.
Now if you're sending people to a website, you can get a specific domain for each advertising campaign you're running.
Another thing you can do is put a code on the flyer and when you create your lead capture page, have a place on there for a code. You can even offer your prospects a free gift for inputting the code from their flyer to the lead capture page.
Those are the simple ways to track your offline marketing efforts.