Does an injective $\mathbb F_9$ vector space homomorphism $\mathbb F_9^3 \to \mathbb F_9^5$ exist?
Is it able to solve that task by some technique? If so, how is it working then?
I have posted a similiar question here but with a mapping that is not a homomorphism.
Yes. For example, consider the map which sends $(a,b,c)\in \mathbb{F}_9^3$ to $(a,b,c,0,0)\in \mathbb{F}_9^5$.