Yes you could still get pregnant. Condoms have about a 15% rate of failure, generally due to when they are not used properly, however they are still one of the most effective forms of birth control, and the best way to protect against STDs. In most cases it's always a good idea to use a back-up method as well.
A condom is a form of birth control. So if you meant to ask, if you use a condom without an oral contraceptive, can you still get pregnant?....... The answer is yes. If the condom doesn't fit or breaks you can get pregnant. The only 100% guarantee is abstinence.
Even the condom + backup isn't always enough. It always amazed me when I used to work in daycare just how quickly we would've been out of business if that wasn't the case. At one time, according to things we were told by the parents, 9 of the 15 babies we had enrolled were "pill babies".