how to fit outside temperature sensor to 54 peugeot 206 se 1.4 petrol 16v?

How do I fit an outside temperature sensor to my
54 plate Peugeot 1.4 se petrol 16v I had a look under left hand side mirror it has a hole where the sensor nipple goes but when I took it apart and had a look there was no sensor or wires it is a manual lever mirror.