  Microlensing is one of the most promising tools for discovering stellar-mass
black holes (BHs) in the Milky Way because it allows us to probe dark or faint
celestial compact objects. While the existence of stellar-mass BHs has been
confirmed through observation of X-ray binaries within our galaxy and
gravitational waves from extragalactic BH binaries, a conclusive observation of
microlensing events caused by Galactic BH binaries has yet to be achieved. In
this study, we focus on those with high eccentricity, including unbound orbits,
which can dynamically form in star clusters and could potentially increase the
observation rate. We demonstrate parameter estimation for simulated light
curves supposing various orbital configurations of BH binary lenses. We employ
a model-based fitting using the Nelder-Mead method and Bayesian inference based
on the Markov chain Monte Carlo method for the demonstration. The results show
that we can retrieve true values of the parameters of high eccentric BH binary
lenses within the 1$\sigma$ uncertainty of inferred values. We conclude it is
feasible to find high eccentric Galactic BH binaries from the observation of
binary microlensing events.
