Lock screen when proximity sensor is covered I have a Samsung Galaxy S3 with Jelly Bean. I would like, for, my screen to lock if proximity sensor is covered (for instance, when it is in my pocket). 

How can I do that? 

I am searching for an app as I have not found anything within the standard menu.
Have a look at Smart Cover, Cover Lock, Simple Cover Lock [Beta] and others on Google Play. You can probably find other apps that maybe are better for you by just looking at the 'similar' apps section on Google Play.