We present the results of a systematic investigation of the magnetic properties of the three-dimensional Kondo topological insulator SmB₆ using magnetization and muon-spin relaxation/rotation (μSR) measurements. The μSR measurements exhibit magnetic field fluctuations in SmB₆ below ∼15 K due to electronic moments present in the system. However, no evidence for magnetic ordering is found down to 19 mK. The observed magnetism in SmB₆ is homogeneous in nature throughout the full volume of the sample. Bulk magnetization measurements on the same sample show consistent behavior. The agreement between μSR, magnetization, and NMR results strongly indicate the appearance of intrinsic bulk magnetic in-gap states associated with fluctuating magnetic fields in SmB₆ at low temperature.