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Entanglement contour and R\'{e}nyi contour reflect the real-space
distribution of entanglement entropy, serving as the fine structure of
entanglement. In this work, we unravel the hyperfine structure by rigorously
decomposing R\'{e}nyi contour into the contributions from particle-number
cumulants. We show that the hyperfine structure, introduced as a
quantum-information concept, has several properties, such as additivity,
normalization, symmetry, and unitary invariance. To extract the underlying
physics of the hyperfine structure, we numerically study lattice fermion models
with mass gap, critical point, and Fermi surface, and observe that different
behaviors appear in the contributions from higher-order particle-number
cumulants. We also identify exotic scaling behaviors in the case of mass gap
with nontrivial topology, signaling the existence of topological edge states.
In conformal field theory (CFT), we derive the dominant hyperfine structure of
both R\'{e}nyi entropy and refined R\'{e}nyi entropy. By employing the
AdS$_3$/CFT$_2$ correspondence, we find that the refined R\'{e}nyi contour can
be holographically obtained by slicing the bulk extremal surfaces. The extremal
surfaces extend outside the entanglement wedge of the corresponding extremal
surface for entanglement entropy, which provides an exotic tool to probe the
hyperfine structure of the subregion-subregion duality in the entanglement
wedge reconstruction. This paper is concluded with an experimental protocol and
interdisciplinary research directions for future study.