  Unrevealing local magnetic and electronic correlations in the vicinity of
charge carriers is crucial in order to understand rich physical properties in
correlated electron systems. Here, using high-energy optical conductivity (up
to 35 eV) as a function of temperature and polarization, we observe a
surprisingly strong spin polarization of the local spin singlet with enhanced
ferromagnetic correlations between Cu spins near the doped holes in lightly
hole-doped La$_{1.95}$Sr$_{0.05}$Cu$_{0.95}$Zn$_{0.05}$O$_{4}$. The changes of
the local spin polarization manifest strongly in the temperature-dependent
optical conductivity at ~7.2 eV, with an anomaly at the magnetic stripe phase
(~25 K), accompanied by anomalous spectral-weight transfer in a broad energy
range. Supported by theoretical calculations, we also assign high-energy
optical transitions and their corresponding temperature dependence,
particularly at ~2.5 ~8.7, ~9.7, ~11.3 and ~21.8 eV. Our result shows the
importance of a strong mixture of spin singlet and triplet states in hole-doped
cuprates and demonstrates a new strategy to probe local magnetic correlations
using high- energy optical conductivity in correlated electron systems.
