USB-C has a mode to run analog audio over its cable, called "Audio Adapter Accessory Mode." It uses the D+ and D- pins for Right and Left, and SBU1 and SBU2 for Mic and Ground.
Texas Instruments explains the scheme in a document, "tidub66.pdf."
I know USB-C connectors aren't quite what you had in mind, but they are smaller and more rugged than the 3.5mm connector (in my opinion).
Downside is it is not widely supported, but it is possible. The host device needs to support a way to detect the analog USB-C audio cable (recognized through four shorted pins) and then to split off the analog audio signals before they hit the internal USB transceiver chip.
Texas Instruments explains the scheme in a document, "tidub66.pdf."
I know USB-C connectors aren't quite what you had in mind, but they are smaller and more rugged than the 3.5mm connector (in my opinion).
Downside is it is not widely supported, but it is possible. The host device needs to support a way to detect the analog USB-C audio cable (recognized through four shorted pins) and then to split off the analog audio signals before they hit the internal USB transceiver chip.