Issue wit horn and headlights

[Giliador]

When driving suddenly my horn start beeping even after engine was off it continue to beep in addition headlight went on and stay on. I removed the fuse for the horn but to stop battery from going flat I have to unplug it every time I park otherwise headlight will not go off (its a 2016 Yaris no automatic headlights) Book it in to Toyota, they told me there was no problem and everything seems to work, after 2 weeks again, car is parked horn suddenly start beeping headlight is on. Booked the car for Wednesday I'm worried again by the time I bring the car it will stop, lucky I was around the car I'm worried of this happening at night or when I'm not around the car, any suggestions what could be the cause?
Thanks