The paper introduces a novel technique called cavity-enhanced photoacoustic dual-comb spectroscopy (Cavity-DEPACS), which combines the strengths of cavity-enhanced photoacoustic (C-PA) and dual-comb spectroscopy (DCS) to achieve ultrasensitive, broadband, and high-resolution molecular spectroscopy. The method overcomes the limitations of conventional DCS by using a high-finesse optical cavity to amplify the power of dual-frequency combs and a broadband acoustic resonator with a flat-top frequency response. This setup enables the detection of trace amounts of gases such as C₂H₂, NH₃, and CO in the telecommunications C-band with a minimum detection limit of 0.6 ppb for C₂H₂ at a measurement time of 100 seconds, corresponding to a noise equivalent absorption coefficient of 7 × 10⁻¹⁰ cm⁻¹. The Cavity-DEPACS technique demonstrates significant improvements in detection sensitivity and broad bandwidth compared to traditional methods, making it a powerful tool for advanced spectroscopic measurements and gas sensing applications.The paper introduces a novel technique called cavity-enhanced photoacoustic dual-comb spectroscopy (Cavity-DEPACS), which combines the strengths of cavity-enhanced photoacoustic (C-PA) and dual-comb spectroscopy (DCS) to achieve ultrasensitive, broadband, and high-resolution molecular spectroscopy. The method overcomes the limitations of conventional DCS by using a high-finesse optical cavity to amplify the power of dual-frequency combs and a broadband acoustic resonator with a flat-top frequency response. This setup enables the detection of trace amounts of gases such as C₂H₂, NH₃, and CO in the telecommunications C-band with a minimum detection limit of 0.6 ppb for C₂H₂ at a measurement time of 100 seconds, corresponding to a noise equivalent absorption coefficient of 7 × 10⁻¹⁰ cm⁻¹. The Cavity-DEPACS technique demonstrates significant improvements in detection sensitivity and broad bandwidth compared to traditional methods, making it a powerful tool for advanced spectroscopic measurements and gas sensing applications.