  Proton-proton interaction and photo-hadronic interaction in cosmic
accelerators are the two main channels for the production of cosmic ultra-high
energy photons and neutrinos (TeV-PeV). In this Letter, we use FWW approach to
obtain the production of cosmic ultra-high energy photons and neutrinos from
the collision between UHE proton with magnetic field which could be considered
as the virtualphoton in the rest frame of UHE proton. We name this as $pB$
process. The threshold for the occurrence of the $pB$ process is that the
combination of the Lorentz factor of proton and the strength of the magnetic
field is about $\gamma_p B \simeq 5\times 10^{18}$Gauss. Beyond this threshold,
the rate of energy loss of proton due to the $pB$ process is about three orders
higher than that due to the synchrotron radiation of proton in the same
magnetic field. The $pB$ process might potentially happen in the atmosphere of
white dwarfs, neutron stars or even that of stellar massive black holes.
