Switch between two low voltage signal sources
You could use an analog(ue) switch - these are basically open/closed contacts in silicon controlled from a logic signal: -



There are sub-1ohm varieties but you can buffer the signal (in or out) with a high impedance op-amp circuit.

Functionally they look like this (DG273): -



But can be much more complicated offering the ability to multiplex several signals to one line. Here is a guide from Texas Instruments.