Will expunged records come up on a Secret Clearance?

a little over a year ago i was caught on my college campus with a tiny amount of marijuana and charged with a misdemeanor of possession of marijuana. My lawyer told me the best thing to do would go to the county jail for 3 days, as opposed to doing a year of probation and other requirements, in which case afterwords i could get it expunged and no one would be able to see it on my record. however, my lifelong goal has been to become a Marine and specifically Marine Recon. one of the requirements of Marine Recon is you have to be able to obtain a Secret Clearance. im worried that the Marines will be able to see this on my record because i figured if the government really wants to find something they can and will. or does expunged basically disappear all evidence of the situation of ever happening? id appreciate it if only people who have experience in either fields (military, law, or other) would answer and cite your source, thanks.