Any audio recorder or spy camera would emit a wireless signal whereas wired signals were used for official equipment like security cameras and the like. Therefore, it was not hard to detect these things. The simplest method, if one did not have a specialized device to detect wireless signal, was to turn on one's phone or wireless radio and walk around the place. If there was an interruption to the sound, there was a wireless signal nearby. However, people would not normally do that. This was not a spy film, who would be so free‽
It had to be said that Han Chu knew his friend well. That golden retriever had managed to plant a bug inside the slit of the sofa from a simple visit. If not for Ye Shuang's superhuman hearing, discovering that bug would not have been easy.
