  Monitoring mass accretion onto substellar objects provides insights into the
geometry of the accretion flows. We use the Lulin One-meter Telescope to
monitor H$\alpha$ emission from FU Tau B, a $\sim$19 $M_{\rm Jup}$ brown-dwarf
companion at 5.7" (719 au) from the host star, for six consecutive nights. This
is the longest continuous H$\alpha$ monitoring for a substellar companion near
the deuterium-burning limit. We aim to investigate if accretion near the
planetary regime could be rotationally modulated as suggested by magnetospheric
accretion models. We find tentative evidence that H$\alpha$ mildly varies on
hourly and daily timescales, though our sensitivity is not sufficient to
definitively establish any rotational modulation. No burst-like events are
detected, implying that accretion onto FU Tau B is overall stable during the
time baseline and sampling windows over which it was observed. The primary star
FU Tau A also exhibits H$\alpha$ variations over timescales from minutes to
days. This program highlights the potential of monitoring accretion onto
substellar objects with small telescopes.
