Baking a displacement map with Blender 2.8 and Cycles?

I want to achieve a greyscale displacement map, like this one:

I have a model and another model which has been modified using a displacement modifier, now I want to bake that displacement into the uv map.

Following this awesome tutorial I was able to generate a normal map, however I see no displacement in the bake type selection.

How do I make a displacement map instead?

Here is the blendfile if anyone wants to take a look.

It’s because you can bake on which direction ray hitting UV is hitting your mesh, but you can’t tell how high is it in regard to… right, what?
To bake displacement you have to unwrap your model so it’s completly flat, position it on 0x0x0, set shader to emission with strength of 1 with no light falloff, set bounces to 0, camera to ortographic view, position it on top of that and connect texture to gradient, scale it so max value is white and min value is black. Then you can render image and use it as displacement map.
I’ve done this with my meadow scene, check out here:

Related to the original model, (granted it must have the same vertices/faces) for example to bake the normal map you select the two models, and the result is the difference between the two.

With your scene it’s quite easy to bake the displacement.

The trick is:
Bake the Object_coordinates from the lowres into a file (32b Float).
On the hires object, subtract the baked texture from the object coordinates with a vector math node.
For vector displacement: just bake the result subtraction.
For float displacement, plug the subtracted vector into both inputs of a vector math node, set it to Dot operation, and bake the square root of the Value output (with a math node, op=power, second input set to 0.5).

I need to bake these scales on that plane so is there a quick way of doing it in 2.8 or i am stuck at exporting to 2.79?