My laptop bag, what's this for?

I have an old Targus laptop carrying case, hangs from my shoulder with a
strap, and on the strap is another little container the size and shape
of 2 of my larger fingers.  It closes with velcro at the top end. 

I can't figure out what it's for. 

Maybe an early very little phone would fit but it woudn't be very handy.
The same bag has an opening to the main bag for headphone wires.