Recent studies have shown that root system architecture determines crop resilience and productivity. However, roots grow invisibly underground and are notoriously difficult to track. Root visualization requires digging, which is time-consuming and destructive. The lack of real-time non-invasive underground imaging methods has made it challenging to study this vital organ. Here, we report a method for imaging underground root system using the distributed fiber optic sensor. device named "Fiber-RADGET". By formulating an optical fiber into spiral polytetrafluoroethylene film, the sensor device named Fiber-RADGET detects and monitors geophysical strain generated by root development. Agricultural technology is increasingly becoming automated with seamless feedback through Internet-of-Things remote sensors. The device highlighted here represents a significant addition to the repertoire of tools that next-generation agriculturalists can use for data-driven automation.