We performed all experiments with a custom build field cycling setup based on Bruker 400 MHz Avance HD NMR spectrometer, which allows to comprise magnetic field cycling, parahydrogen bubbling, and light irradiation within a single experiment using a standard NMR screw cap sample tube (Fig. .A). To vary magnetic field from microtesla to nanotesla range we exploit three-layer magnetic shield, equipped with the inductive coil system for magnetic field control and shimming (Fig. .B). Stepper motor allows to transfer the carriage with the mounted sample between the spectrometer detection zone and the magnetic shield, located at the top of the spectrometer bore, in 0.4 second. The parahydrogen bubbling is performed with an automatic high-pressure gas system, controlled with transistor-transistor logic (TTL) valves. To irradiate the sample with light, we utilize seven diode lasers with 450 nm wavelength and 170 mM optical power of each one triggered by TTL pulse from NMR console (Fig. .D). Powerful light irradiation allows to increase the transition rate between trans and cis ABZ, which turned out to be crucial for photo-SABRE. In order to minimize the impact of the lasers on the homogeneity of the ultra-low field inside the magnetic shield, the lasers were positioned outside the shield, just above its upper edge.