If you can’t feel your hand heating up if you hold it near the oven and sensors or thermometer strips don’t register any temperature increase outside the oven when it’s on then nothing substantial is escaping. The amount of 2.4ghz energy required for indoor communication is on the order of tenths or hundredths of a watt, whereas the amount of energy required to cook food is on the order of 1000 watts. So you’re talking about a 10,000-100,000-fold difference in magnitude.

For non-ionizing EM radiation like radio waves and normal light (as opposed to ionizing radiation that can cause cancer by knocking bits off your DNA like UV rays and X rays) the danger is in, essentially, cooking your flesh. For radio professionals determining if a microwave antenna or cell phone is safe for your body, we calculate watts per square centimeter, in other words how much electrical energy is delivered to your skin’s surface. When a radio professional messes up and gets exposed to dangerous levels of energy, they experience it as feeling very warm or burning, and may suffer symptoms similar to a sunburn or, worst case, like putting a body part in a microwave oven.

Also because of how rays of energy work mathematically against surfaces, every foot you stand away will exponentially decrease the amount of energy you’d possibly receive: standing 6 feet away will give you 2.8% the dose versus standing 1 foot away. So even if you have a dangerously defective oven, just don’t hang out with your face pressed to the glass and you’ll have much bigger things to worry about in life.

TLDR: there’s no voodoo scariness behind microwaves, just try to make sure they’re not warming you up and cooking you, especially for extended periods of time. You’d probably notice if they were.

The main hazard of putting an electronic device in a microwave is that it heats up and catches fire or ruins your food.