The moon gets hit all the time. They're recorded as flashes usually classified as transient lunar phenomena. The reason reason they don't just call them impacts is because not all are impacts. Some are believed to be flashes caused by static electricity or other little understood phenomenon.
At between 250,000 and 500,000 miles a flash needs to be pretty big to be seen with the naked eye and few are. If a nuke were detonated on the moon its pretty likely that it would go unnoticed by anyone not watching for it.
Tons of meteors enter our atmosphere every day but most are the size of grains of sand and burn up in our atmosphere. Obviously the moon gets hit by the same but they're so small that we're not going to see them.
Transient lunar phenomenon