Sub-terahertz frequency band is beneficial for radio access networks of the sixth generation. Due to rather limited power capacity, there appears a necessity to equip transmitters and receivers in sub-terahertz wireless channels with high directivity antennas. This, however, leads to a potential connection failure in response to even a minor linear or angular displacement of a user equipment. This article is focused on a hardware- and user-induced micromobility effects for different scenarios of in-door radio access at carrier frequency of 140 GHz. The developed measurement setup enables fast simultaneous logging of linear and angular displacements of a user equipment with respect to radio access point and the corresponding received signal strength. Experimental data is processed by Allan variance analysis, statistics is acquired for a large number of samples. We believe that our findings should be of use in the development of beam steering solutions for reliable sub-terahertz wireless communications.