"They" won't find out via polygraph when you're just another OCS candidate. But--if you stay "in the club" and promote, they're going to ask you again and again as you renew your clearance, and at some point they'll probably want to hook you up to the machine. Do you really want to remember "a story" for twenty years? We don't hire angels...we hire leaders. Honor, courage, commitment are simple concepts. Don't make it overly complicated. Say what you did, let 'em know you understand what "zero tolerance" means, and let 'em know why it matters to you. "They" will usually make the right decision. I'd rather have an officer in the wardroom who admitted they smoked dope 10 years ago, than an officer who just "lied again" on their clearance renewal. The first one USED to smoke dope, the second one IS a liar. Big difference.
Generally good advice, but that's not how they do polygraphs for a clearance.
Brett