I believe this story happened with the Chidushei HaRim. He was reknowned for his brilliance even at a very young age. A chossid was in his town and visited his home and wanted to see if his reputation was valid. He said to the young boy “I will give you three ruble if you can tell me where Hashem is”. The young boys eyes lit up, and immediately responded “I will give you 6 ruble if you can tell me where Hashem isn’t”.
(I’m not sure if the visitor gave the boy the rubles, but he was surely impressed!)