Someone who is not in the military is prohibitted to wear a military uniform. Simalarly someone not in yeshiva is prohibited to wear the Yesivah uniform.
Except as otherwise provided by law, no person except a member of the Army, Navy, Air Force, or Marine Corps, as the case may be, may wear –
(1) the uniform, or a distinctive part of the uniform, of the Army, Navy, Air Force, or Marine Corps; or
(2) a uniform any part of which is similar to a distinctive part of the uniform of the Army, Navy, Air Force, or Marine Corps