We report photometric observations of the hidden symbiotic star SU Lyn in the optical bands. In five nights we detect a weak flickering in U band with amplitude of about 0.05 magnitudes. No intranight variations are found in B, V, g' and r' bands. This is one more indication that the secondary component is a white dwarf accreting at low accretion rate. We also searched for intranight variability of a dozen related object (RR Boo, RT Boo, AM Cyg, AG Peg, BF Cyg, NQ Gem, StHa190, V627 Cas, XX Oph, FS Cet and Y Gem) in which no variability above the observational errors is detected.This work is part of the project KP-06-H28/2 08.12.2018 ”Binary
stars with compact object” (Bulgarian National Science Fund). DM and BB acknowledge
project RD-08-100/2022. JM and PLE acknowledge support from Programa Operativo
FEDER 2014-2020 and Consejer´ıa de Econom´ıa y Conocimiento of Junta de Andaluc´ıa (Ref.
1380270)