Help identifying and figuring out how to turn on bathtub faucet

[Dante R]

I am rather clueless when it comes to plumbing and have been searching around the internet to no avail. All I have figured out is that this is a moen trim because of the visible branding, but other than that I am lost. The handle pulls out to start running the shower, and turning it left or right determines hot/cold. The handle does not turn all the way around.

I also cannot seem to figure out how to turn the bathtub faucet on. The little thing under the handle looks like some kind of button but I can't press it in. (and I can't figure out if that's due to rust/build-up or if it's because it's not a pressable button )

Any and all help/feedback is greatly appreciated because this mystery is driving me crazy.

 

[JohnjH2o1]

That little button needs to pull out. When it's in it diverts the water to the shower. The part is replaceable.

 

[Sponsor]

 

[Terry]

The tub spout has a diverter and the shower has a diverter.
For water to go to the tub, the spout diverter is down and the handle diverter is out.

Normally with a diverter shower handle you would not have a spout with a diverter. It rather confuses things.