Have your backyard lights come on automatically just as soon as you open your back door. Normally you would just flick the wall switches on, plug in the gazebo lights, or whatever else and then enjoy your evening outside. You can just simply have a door sensor, smart lights or smart switches for the regular lights, or smart plugs to turn on plugged lights such as string lights and they all will be automated. Open the door, and they all trigger. They can all turn off by itself as well when you go inside and close the door. You can do whatever you want with that! It can be set on a schedule as well, as well as be triggered only during specific times. That means, they do not come on if you open the door during daytime, but they will be triggered between dusk to dawn. (Or fixed times, if you prefer)
You can have smart motion sensors or smart cameras toggle them all on if it sees motion. It would likely be a better deterrent to people trying to break into the backyard. Many of them are used to standard motion sensor lights and would ignore it. But if your lights, gazebo lights, and everything else comes on, that would be a little more of a deterrent. They would probably think why is everything coming on? Someone’s coming outside and run away.
Smart devices used here: SmartThings multipurpose sensor (used as a door sensor), LIFX light bulbs and Wemo Switch.