  Heavy neutral leptons $N$ are introduced to explain the tiny neutrino masses
via the seesaw mechanism. For proper small mixing parameter $V_{\ell N}$, the
heavy neutral leptons $N$ become long-lived, which leads to the displaced
vertex signature at colliders. In this paper, we consider the displaced heavy
neutral lepton from the neutrinophilic Higgs doublet $\Phi_\nu$ decay. The new
Higgs doublet with MeV scale VEV can naturally explain the tiny neutrino masses
with TeV scale $N$. Different from current experimental searches via the
$W^\pm\to \ell^\pm N$ decay, the new decays as $H^\pm\to \ell^\pm N$ are not
suppressed by the small mixing parameter $V_{\ell N}$. Therefore, a larger
parameter space is expected to be detected at colliders. We then investigate
the promising region at the 14 TeV HL-LHC and the 3 TeV CLIC. According to our
simulation, the DV signature could probe $|V_{\ell N}|^2\gtrsim10^{-19}$ with
$m_N<m_{H^+}$, which covers the seesaw predicted value $|V_{\ell N}|^2\sim
m_\nu/m_N$. We could probe $m_{H^+}\lesssim1200$ GeV at the 14 TeV HL-LHC and
$m_{H^+}\lesssim1490$ GeV at the 3 TeV CLIC.
