  Various types of electroweak-interacting particles, which have non-trivial
charges under the $\mathrm{SU}(2)_L \times \mathrm{U}(1)_Y$ gauge symmetry,
appear in various extensions of the Standard Model. These particles are good
targets of future lepton colliders, such as the International Linear Collider
(ILC), the Compact LInear Collider (CLIC) and the Future Circular Collider of
electrons and positrons (FCC-ee). An advantage of the experiments is that, even
if their beam energies are below the threshold of the production of the new
particles, quantum effects of the particles can be detected through high
precision measurements. We estimate the capability of future lepton colliders
to probe electroweak-interacting particles through the quantum effects, with
particular focus on the wino, the Higgsino and the so-called minimal dark
matters, and found that a particle whose mass is greater than the beam energy
by 100-1000 GeV is detectable by measuring di-fermion production cross sections
with $O(0.1)$\% accuracy. In addition, with the use of the same analysis, we
also discuss the sensitivity of the future colliders to model independent
higher dimensional operators, and found that the cutoff scales corresponding to
the operators can be probed up to a few ten TeV.
