Wouldn’t an admission officer or a professor who is looking at the application ask about the violation if it’s in the record? In most such cases, it’ll likely result in an automatic rejection unless the violation is well, and convincingly, explained by the applicant.
I don’t recall if the question of honor code violation or other infractions in college is specifically asked on an application to all grad schools (grad school applications are school-specific), but I’d suppose most do. I believe such questions (regarding infractions while in high school) are even on the common/coalition apps for college admissions.