Can I use 240v wiring in 120v system for lights?

Thanks

Wire that is good for 240 volts is good for 120. Do you mean 240 volt bulbs, or 2 120 volt bulbs in series?

The rating of wiring can meet or exceed the rating of the devices on the circuit, just the voltage cannot exceed the voltage rating of the devices.

Isn't most of the common stuff such as NM-B, THHN, etc. all rated for 300 volts?

Just to make sure... you aren't talking about an existing 240V circuit that you are trying to convert to a 120V circuit are you? That's an entirely different animal. It can be done, but requires some work in the panel.

The standard wiring is rated for 600 volts.