Short answer
Action potentials travelling through the axon are accompanied by a mechanical displacement of the axonal membrane.
Background
Multiple studies have shown that a mechanical displacement of the axonal membrane accompanies an action potential. Hady & Machta (2015) used a computer model to show that these mechanical displacements are generated by the storage of energy in the neuronal membrane when the action potential travels through the axon that alter the compressive electrostatic forces across the membrane. These forces lead to co-propagating mechanical displacements accompanying the action potentials, which the authors have dubbed 'action waves' (Hady & Machta, 2015).
It is important to realize that the action potential drives the action wave and communication between neurons. As far as I understand, the action wave has no known physiological function in neural communication, although it is a point of debate (Fox, 2018).
Reference
- Fox, Sci Am (2018), April issue
- Hady & Machta, Nat Comm (2015); 6: 6697