Is it permissible for an employee to take consumables of negligible value, such as milk, tea, coffee, and tissues, from an American computer company that has not paid him his salary for 11 months, in order to compensate for a part of his usurped right?

If you have a confirmed right against a company, and you cannot recover it except by taking money from them without their knowledge, then there is no blame upon you for taking what is equal to your right or less than it. This is known as the "issue of al-Dhafr" (taking one's right by force or stealth). Al-Bukhari and Ibn Sirin deduced the permissibility of this, and while the scholars differed on it, the preponderant opinion is that it is permissible.