Aspects of the subject disclosure may include, for example, receiving, by a receiver of a first device, electromagnetic waves that are generated by a transmitter of a second device at a physical interface of a transmission medium, where the electromagnetic waves propagate without requiring an electrical return path, and where the electromagnetic waves are guided by the transmission medium to the receiver of the first device. The first device can detect a physical object in proximity to the transmission medium according to a change in the parameter associated with the electromagnetic waves. Other embodiments are disclosed.