Go to UVs & Maps > Extract Texture Maps > New operation... and in the following dialog select Vector Displacement Map.
For Target Models select the 0-level resolution of the object. For Source Models select the resolution that you want to bake (typically the highest resolution) - in this case, level 4.
Here, we enable the Smooth Target Models and Use Creases & Hard Edges options and disable the Smooth Target UVs. Whether to choose these options depends on the model you are exporting. With this particular model, we want to keep the hard edges in order to keep the "edgy" look at the alien's neck.
Similar to that, we enable the Smooth Source Models option, which affects the polygonal faces of the highest res mesh (level 4) .
Set the desired resolution of the displacement map. A resolution of 2048x2048 works in our case.
Set the Vector Space to Object.
It is important to choose the same Vector Space mode as the Displacement type used later in V-Ray for Maya.
Select an OpenEXR file as the output vector displacement file, that is the Base File Name. V-Ray supports 32-bit maps, so it is better to keep the Bits per Channel to 32-Bit FP.
Once ready with all the settings, press the Extract button to create the vector displacement map.