Can I sue a company for getting robbed by one of their employees

Here is the applicable law: an employer is liable for the tortious acts of its employee when the employee is acting within the course and furtherance of his employment (this is the doctrine of "respondeat superior," or, "let the master answer" for the sins of the servant). It is extremely unlikely that it was part of the employee's job duties to rob you, and the employer will have little difficulty proving this. Indeed, I imagine that you would likely concede it. Rather than doing his employer's bidding by robbing you, the employee was on a so-called "frolic and detour," although you may misread this to belittle the extent of the harm that has befallen you. In general, an employer is not liable for an employee's tortious acts committed during a frolic and detour.