As far as I know- yes. There are plenty of topics on the forum about people's spiritual pals who aid them in practice. Keep in mind that spiritual creatures come in all kinds- demons, astral dragons, spirits of the deceased, you name it! You'll have to learn how to get in touch with one and ask for it to stay by your side as a companion. Emphasis on companion. Spirits are not pets who will follow your every whim. Like humans they have varying personalities and goals of their own.They generally don't take kindly to being bossed around. However this all really depends on the spirit.
In general, what I suggest is meditation and doing some research on spirits to find out how to contact one and gain its trust. You do not need to be a witch or psychic- just take your time and develop your abilities.
TLDR: It's possible, you just need study and practice ;)