A mechanical mass sensor with yoctogram (10^-24 g) resolution has been developed using a carbon nanotube resonator. The resonator, approximately 150 nm long and vibrating at nearly 2 GHz, achieves a mass resolution of 1.7 yg, equivalent to the mass of a single proton or hydrogen atom. This unprecedented sensitivity allows detection of single naphthalene molecules and measurement of xenon atom binding energy on the nanotube surface (131 meV). The sensor's high sensitivity is achieved through a combination of a short nanotube, ultra-high vacuum, and low-noise motion detection. The nanotube is annealed with a large current to reduce fluctuations and improve sensitivity. The device's performance is validated through measurements of adsorption events and binding energy, demonstrating its potential for applications in mass spectrometry, magnetometry, and adsorption studies. The sensor's ability to detect individual atoms and molecules opens new possibilities for high-resolution mass sensing and chemical analysis. The study also shows that the binding energy of xenon atoms on nanotubes is significantly lower than on graphite, due to nanotube curvature and multiple graphene layers. The results highlight the potential of nanotube resonators for future scientific and technological applications, including high-sensitive magnetometry and advanced mass spectrometry. The sensor's design and performance are supported by theoretical analysis and experimental validation, demonstrating its potential for further development in nanoscale sensing technologies.A mechanical mass sensor with yoctogram (10^-24 g) resolution has been developed using a carbon nanotube resonator. The resonator, approximately 150 nm long and vibrating at nearly 2 GHz, achieves a mass resolution of 1.7 yg, equivalent to the mass of a single proton or hydrogen atom. This unprecedented sensitivity allows detection of single naphthalene molecules and measurement of xenon atom binding energy on the nanotube surface (131 meV). The sensor's high sensitivity is achieved through a combination of a short nanotube, ultra-high vacuum, and low-noise motion detection. The nanotube is annealed with a large current to reduce fluctuations and improve sensitivity. The device's performance is validated through measurements of adsorption events and binding energy, demonstrating its potential for applications in mass spectrometry, magnetometry, and adsorption studies. The sensor's ability to detect individual atoms and molecules opens new possibilities for high-resolution mass sensing and chemical analysis. The study also shows that the binding energy of xenon atoms on nanotubes is significantly lower than on graphite, due to nanotube curvature and multiple graphene layers. The results highlight the potential of nanotube resonators for future scientific and technological applications, including high-sensitive magnetometry and advanced mass spectrometry. The sensor's design and performance are supported by theoretical analysis and experimental validation, demonstrating its potential for further development in nanoscale sensing technologies.