Individual electron spins in semiconductor quantum dots are exemplary quantum objects because they can possess extremely long phase coherence times, in some cases exceeding one second. Such long coherence times makes spins a versatile platform for exploring quantum information processing and sensing. I will give an overview of recent work exploiting the joint spin-state of two electrons in a GaAs double quantum dot as a quantum bit, or qubit. This qubit is highly sensitive to its local magnetic environment, and we leverage this sensitivity to precisely measure the statistically fluctuating nuclear polarization in the semiconductor crystal. Surprisingly, we can harness the random nuclear polarization in the semiconductor to suppress electrical decoherence in the spin qubit, enabling a high-fidelity entangling gate between spin qubits.