I dont beleive in lying to parents. I told my parents where i was going the first time i ever bought weed, and i told them i was going to smoke it. They didnt like the idea, but once i had it, they were fine with it, and still are to this day, i even got my dad smoking a little bit of hash with me, and my mum loves the smell, so when im around at their house i always take a little bit of each.

Just tell your parents that you smoke, then you wont get caught [at least by them]

And if you arrested, it'll be a massive shock for them, you should be able to tell your parents anything, so do it. You may be surprised.