  The Compact Linear Collider (CLIC) is a proposed TeV-scale high-luminosity
electron-positron collider at CERN. The first CLIC running stage, at 380\,GeV,
will focus on precision Higgs boson and top quark studies while the main aim of
the subsequent high-energy stages, at 1.5 TeV and 3 TeV, is to extend the
sensitivity of CLIC to different Beyond the Standard Model (BSM) scenarios.
  We studied the prospects for measuring invisible Higgs boson and additional
heavy scalar decays using CLIC data at 380 GeV and 1.5 TeV. The analysis is
based on the WHIZARD event generator, with fast simulation of the CLIC detector
response parametrised by the DELPHES package. We present the expected limits
for the invisible decays of the 125 GeV Higgs boson, the cross section limits
for production of an additional neutral Higgs scalar, assuming its invisible
decays, and limits on the mixing angle between the SM-like Higgs boson and the
new scalar of the "dark sector" in the framework of the vector-fermion dark
matter model.
