Rolling codes are better. But if you haven't seen it, Samy Kamkar has a device called Roll Jam, take a look at the last ~5 mins of this Defcon23 talk: https://www.youtube.com/watch?v=UNgvShN4USU
(The TL;DR of the trick there is: Jam the radio signal a key fob sends so a car/garage fairly wide band receiver can't hear it. At the same time listen with a better tuned receiver. Wait for someone to press their key fob and record the code, then wait for them to press it again and record the second code - then stop jamming and replay the 1st code you captured. Door opens and person goes through. But you now have a valid second rolling code that will work. You can do this with a Teensy3 and two CC1101 modules, about $40 worth of hardware.)