Studies of free-floating planets (FFPs) are one of the main focus of microlensing research nowadays. In order to estimate the masses of the FFPs, we would need to measure their microlensing parallaxes either by detecting subtle changes in the light curves caused by different locations of observatories on the Earth or by observing the event from the ground and from space. Such measurements have not yet been done. In order to measure the microlensing parallax of FFPs, a microlensing campaign was conducted by the K2 space mission. A recent analysis of the K2 bulge data by McDonald et al. (2021) revealed four candidates for FFPs. We searched ground-based archival datasets for microlensing signals and detected such a signal only for one of them: K2C9-2016-BLG-1 in the KMTNet data. I will present a joint analysis of K2C9 and KMTNet data for this event.