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We investigate accessibility and controllability of a quantum system coupled to a quantum probe , both described by two-dimensional Hilbert spaces, under the hypothesis that the external control affects only . In this context accessibility and controllability properties describe to what extent it is possible to drive the state of the system by acting on and using the interaction between the two systems. We give necessary and sufficient conditions for these properties and we discuss the relation with the entangling capability of the interaction between and . In particular, we show that controllability can be expressed in terms of the SWAP and operators acting on the composite system.