In this image, an xpDeformer has been made the ‘child’ of a Plane and the particles, with their velocity dictated by the xpTurbulence modifier, are deforming the parametric Plane object as they move throughout the animation.
As with any other deformer, the xpDeformer must be a child of the object to be deformed, then an emitter must be present in the Emitter link field.
Once you have done that, there are a number of steps to set up in the xpEmitter.
You must:
Set the Emitter Shape, preferably to Object, and drag the source object into the emitter's Object field; ideally this should be the object to be deformed, but it doesn't have to be.
Set Emit From to Points, to generate particles from the object's vertices.
Check the setting, One Particle Per Source Element, in the xpEmitter - this guarantees that one, and only one, particle will be emitted from each vertex in the object each frame.
Note: This means that the Birthrate setting is ignored, since the Birthrate now depends on the number of vertices in the object.
In the Emission tab, turn off Emit all Frames and set the emitter to emit particles in just one frame.
You don't have to do this - it won't affect the deformer - but if you don't you will generate far more particles than you actually need, which may slow down playback.
Now, set any other emitter parameters, such as Speed, Initial Direction, and so on.
Remember that Birthrate value is ignored if you turned on Emit One Particle Per Point.
One other thing you can do is add a vertex map to the object to be deformed, then drag it into the Selection field, in the emitter's Object tab.