How do you make an app in mit app inventor that runs in background?

how to make an app in mit app inventor that runs in background

Please search the community before asking any question. This has been asked many times before.

https://community.appinventor.mit.edu/search?q=run%20background

I know that i can use tasker extension but i need to call a certain function that checks that is the data of firebase has changed. But i cannot find out that how i can do this.

What extension is that? You mean this

Yes, that's only the extension