The only way your parents would find out, like @old said, is if they happen to know your parents. Jobs have many different employees applying for their positions they aren't going to take time to rat on a teenager who they found out smokes. They're looking for the best possible person for that job, they aren't looking to bust kids. The only thing I could think of your parents being suspicious is if you end up telling them you didn't get the job and they ask you why. It'd be pretty easy to get around though, just tell them someone older applied and they were looking at him more.