User experience (UX) research has traditionally relied on subjective methods like surveys and interviews, yet these often fail to capture the subconscious dimensions of user interaction. This study explores integrating eye-tracking and biometric feedback-physiological tools that measure gaze behaviour and bodily responses-as robust methods for assessing user engagement and cognitive load in digital interfaces. Drawing on empirical evidence, practical applications, and recent advancements from 2023-2025, we argue that these technologies provide a granular, objective lens into user behaviour, complementing qualitative insights. We present new experimental data, detail our methodology, and situate our work within both foundational and contemporary literature. Challenges such as data interpretation, ethical considerations, and technological integration are addressed, positioning these tools as pivotal for advancing UX design in an increasingly complex digital landscape.