  We propose an entanglement-enhanced sensing scheme that is robust against
spatially inhomogeneous always-on Ising interactions. Our strategy is to tailor
coherent quantum dynamics employing the Hilbert-space fragmentation (HSF), a
recently recognized mechanism that evades thermalization in kinetically
constrained many-body systems. Specifically, we analytically show that the
emergent HSF caused by strong Ising interactions enables us to design a stable
state where part of the spins is effectively decoupled from the rest of the
system. Using the decoupled spins as a probe to measure a transverse field, we
demonstrate that the Heisenberg limited sensitivity is achieved without
suffering from thermalization.
