How can I use my iPad Pro as a slave monitor for my MacBook?

IF you want to turn your iPad into a speedy second monitor, there are not many options.

There is Duet monitor or look at Astropad.

These would be the only two I would recommend for using your iPad Pro as a real time second monitor.

What are you needing a second monitor for that you are on the fence about getting a monitor app for your iPad?

http://www.duetdisplay.com/

http://astropad.com/

Good Luck!

I used one called air display the iOS version cost

but the windows / osx clients are free

You generally get what you pay for when it comes to good quality and good reviewed apps.

Not very many users using the Dual Display app, (approx. 60 users )but those that did gave it very mixed reviews.

Get Duet display.

Almost 5000 users using this app and a very large majority of reviews are positive reviews.

Air Display only has about 200 users and, again, the user experience reviews are still mixed with mostly negative reviews.

Don't waste your time with the app you purchased. You're having issues with the app you purchased because it is $1 and not very good, as you have just discovered.

You bought an iPad Pro, get apps that actually work well with it.

Duet display is the way to go.

I use Astropad only because I am a creative and want my large iPad Pro to double as monitor and drawing tablet for my Mac when I use my iPad Pro alongside my Mac.

Most of the better display apps give you the option of going wireless or using your iPad's charging cable connected to your computer's USB ports.

NO other cables needed.

With Astropad on an iPad, it usually works quicker and is a little more accurate and responsive if you connect up the iPad Pro to your computer's USB port while using Astropad.

The other plus is that with USB connected to your iPad while using Astropad, your iPad WILL trickle charged and keep your iPad charged up longer or, at least, slow down the iPad Pro's battery rate of discharge.

Good Luck!