You can use a board of wood under a door knob in a way to help keep doors shut too. They also make bars. That kept robbers out of my grandparents house until police arrived.

https://www.amazon.com/Brinks-675-83001-Commercial-Door-Security/dp/B00NP0E7SI/ref=asc_df_B00NP0E7SI/?tag=hyprod-20&linkCode=df0&hvadid=167148637601&hvpos=&hvnetw=g&hvrand=8052928042577315991&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9008470&hvtargid=pla-305189685809&psc=1

I have this which holds a fair bit of force. If someone "accidentally" unlocks your door and tries to open it, there can be no mistaking. Make sure to test it though.

I dated a guy on the SWAT team for awhile, and he got me one of these. He said if anyone had them on their door, it was almost impossible to ram it in without taking the door frame out. It would keep someone out long enough for you to call for help.

(I actually just use it on my bedroom door)