  We present photometric and spectroscopic observations of SN 2023fyq, a type
Ibn supernova in the nearby galaxy NGC 4388 (D$\simeq$18~Mpc). In addition, we
trace long-standing precursor emission at the position of SN 2023fyq using data
from DLT40, ATLAS, ZTF, ASAS-SN, Swift, and amateur astronomer Koichi Itagaki.
Precursor activity is observed up to nearly three years before the supernova
explosion, with a relatively rapid rise in the final 100 days. The
double-peaked post-explosion light curve reaches a luminosity of
$\sim10^{43}~\rm erg\,s^{-1}$. The strong intermediate-width He lines observed
in the nebular spectrum of SN 2023fyq imply the interaction is still active at
late phases. We found that the precursor activity in SN 2023fyq is best
explained by the mass transfer in a binary system involving a low-mass He star
and a compact companion. An equatorial disk is likely formed in this process
($\sim$0.6$\rm M_{\odot}$), and the interaction of SN ejecta with this disk
powers the main peak of the supernova. The early SN light curve reveals the
presence of dense extended material ($\sim$0.3$\rm M_{\odot}$) at
$\sim$3000$\rm R_{\odot}$ ejected weeks before the SN explosion, likely due to
final-stage core silicon burning or runaway mass transfer resulting from binary
orbital shrinking, leading to rapid rising precursor emission within $\sim$30
days prior to explosion. The final explosion could be triggered either by the
core-collapse of the He star or by the merger of the He star with a compact
object. SN 2023fyq, along with SN 2018gjx and SN 2015G, forms a unique class of
Type Ibn SNe which originate in binary systems and are likely to exhibit
detectable long-lasting pre-explosion outbursts with magnitudes ranging from
$-$10 to $-$13.
