If you don’t want external libraries, use these native Proteus components:

A DC voltage sensor is essentially a voltage divider + ADC input (e.g., to an Arduino).

Example divider:

When using or building a voltage sensor proteus library, you might encounter these errors:

Run the simulation. Open Virtual Terminal. You will see the computed input voltage.

This is your custom voltage sensor library component – reusable by saving as a Proteus sub-circuit.