You can do kinesthesis, which means using your own body to balance weight and create muscle. You can do this inside and there are videos that show you how to do it inside. You can do insanity, which is really easy to acquire…
There are a bunch of exercises you can do at home with no help from weights or equipment whatsoever. Like Lauren said you usually use your own body on these. Some examples could be push-ups, burpees, jumping rope, squats and sit ups. There are many videos and workouts on social media which you can use, or you can even get creative and make them yourself with exercises you like and feel are effective.