A man states, with complete conviction, that his own arm movements are not made by him but are directly controlled by a device implanted by a government agency, and that the fear he feels is likewise put into him by the same device rather than being his own feeling. What is this?

This is a passivity phenomenon: a conviction that one's own actions, movements, or feelings are being controlled or produced by an outside power rather than being one's own, often attributed to a specific external mechanism and held with full delusional conviction. It is not thought insertion, which concerns the alienation of thought specifically, whereas here it is actions and feelings, not thoughts, that are experienced as controlled from outside. It is not an obsession, since the man is not resisting an unwanted thought of his own — he is convinced his actions and feelings genuinely belong to someone else's control. And it is not somatoparaphrenia, which is a false belief about the ownership of a limb, not about who is causing its movement.