  Within the NaCo-ISPY exoplanet imaging program, we aim at detecting and
characterizing the population of low-mass companions at wide separations
($\gtrsim$10AU), focusing in particular on young stars either hosting a known
protoplanetary disk or a debris disk. R CrA is one of the youngest (1-3 Myr)
and most promising objects in our sample because of two previous studies that
suggested the presence of a close companion. Our aim is to directly image and
characterize the companion for the first time. We observed R CrA twice with the
NaCo instrument at VLT in the $L'$ filter with a one year time baseline in
between. The high-contrast imaging data were reduced and analyzed, and in both
datasets the companion candidate was detected. The companion is detected at a
separation of $196.8\pm4.5$/$196.6\pm5.9$ mas ($18.7\pm1.3$/$18.7\pm1.4$ AU)
and position angle of $134.7\pm0.5^\circ/133.7\pm0.7^\circ$ in the first/second
epoch observation. We measure a contrast of $7.29\pm0.18$/$6.70\pm0.15$ mag
with respect to the primary. Stellar proper motion study rejects the hypothesis
of the signal being a background object. The companion candidate orbits in the
clockwise direction and, if on a face-on circular orbit, its period is
$\sim43-47$ yr. This value disagrees with the estimated orbital motion and
therefore a face-on circular orbit may be excluded. Depending on the assumed
age, extinction and brightness of the primary, the stellar companion has a mass
between $0.10\pm0.02\, M_\odot$ and $1.03^{+0.20}_{-0.18}\,M_\odot$ range, if
no contribution from circumsecondary material is taken into account. The
presence of the companion needs to be taken into account when analyzing the
complex circumstellar environment of R CrA.
