At best, that can get you fired. Easily. And that makes it even more difficult to find another job in the future.
More realistically, the (un)likelyhood of a felony conviction going unnoticed on a background check means that whether or not you check the box, if the employer does a background check it will become known, but some places don't run the check and some don't actually care about the results but they're required to run the check.