  The hyperfine interaction between the spins of electrons and nuclei is both a
blessing and a curse. It can provide a wealth of information when used as an
experimental probing technique but it can also be destructive when it acts as a
dephasive perturbation on the electronic system. In this work, we fabricated
large scale single and multilayer isotopically-purified $^{13}$C graphene Hall
bars to search for interaction effects between the nuclear magnetic moments and
the electronic system. We find signatures of nuclei with a spin in the analysis
of the weak localization phenomenon that shows a significant dichotomy in the
scattering times of monolayer $^{12}$C and $^{13}$C graphene close the Dirac
point. Microwave-induced electron spin flips were exploited to transfer
momentum to the nuclei and build-up a nuclear field. The presence of a very
weak nuclear field is encoded in a modulation of the electron Zeeman energy
which shifts the energy for resonant absorption and reduces the $g$-factor.
