This article presents a novel extension to the FAUST programming language called Widget Modulation. Inspired by Modular Synthesizer, this high order operation enables developers to effortlessly implement voltage control type modulation to existing FAUST circuits. Although signal modulation can easily be achieved by writing the necessary code during circuit development, Widget Modulation expressions enable it a posteriori, after the circuit has been developed and without modifying its code. This feature allows for easy reuse and customization without prior planning by the original circuit designer, offering a new level of expressivity and flexibility in FAUST circuit design.