  We address the question of the role of quantum correlations beyond
entanglement in context of quantum magnetometry. To this end, we study the
evolution of the quantum discord, measured by the rescaled discord, of two
electron-spin qubits interacting with an environment of nuclear spins via the
hyperfine interaction. We have found that depending on the initial state the
evolution can or cannot display indifferentiability points in its
time-evolution (due to the energy conservation law), as well as non-trivial
dependence on inter-qubit phase. Furthermore, we show that for initial Bell
states, quantum correlations display a strong magnetic-field sensitivity which
can be utilized for decoherence-driven measurements of the external magnetic
field. The potential discord-based measurement is sensitive to a wider range of
magnetic field values than the entanglement-based measurement. In principle,
entanglement is not a necessary resource for reliable decoherence-driven
measurement, while the presence of quantum correlations beyond entanglement is.
