First, civil servants are not allowed to take part-time jobs. Basically, many examiners are civil servants themselves.
Secondly, every unit has certain opportunities to have staff as examiners every year. Although you have the opportunity to be your future leader, you can only help the person you like in his own unit.
Therefore, it is generally not recommended to believe such a stunt.
If in doubt, please consult the public education enterprises in China.