If the inverting input is low, the op amp it will try raising the output voltage, so via the feedback it will try to match the +15V from the noninverting. As hard as possible. However, at the same time the zener sinks as hard as possible. In the end you get the equivalent of a short circuit and either the opamp, or the zener, will eventually become very hot and might get destroyed.
Realistically, the TL081 is short-circuit protected and the output current capability is not incredibly high, so both parts will just get hot and the output voltage will be somewhere in-between 5 and 15 volts, probably close to 5, because, as said, the current capability is not incredibly high.