Put oil into vacuum reservoir by accident. How do I fix it. ugh

What is your question?

OK, I think I put engine oil in the hole that may be the vacuum reservoir. Now my 1996 box truck engine now screams/screeches and the rpg's seem to be going very fast. Why I think it is the vacuum reservoir is there is a black ball attached to hood that seems to line up perfectly to the hole/drain that I put oil in. How do I fix this? Where did that damn oil go? The box truck is so loud screaming. Help! Thanks, (Not blond but should be) Paula