Outdoor faucet leaking at wall

[leodai]

Hi, I have an outdoor frost free faucet like the picture shown below. I live in Canada, so I have this type of faucet. When I turn on this faucet, I found leaking on the wall (like the picture shown below), but all other parts have no leaking. When I turn off the faucet, the leaking is stopped.
I also checked the parts inside the house, like the second picture shown below. I found no leaking no matter whether the faucet is on or off.
Any thoughts what might be the issue for this case?
Thanks!

 

[Reach4]

Typically this would be caused by you not removing the hose before deep-freezing weather. The valve does not drain out. That copper tube cracks, and lets water out when the valve is opened.

Are you sure it is not the "vacuum breaker"/"antisiphon valve" leaking, and the water drops outside of the valve to where you see it?