I know that philosophers disagree about the meaning of the word
belief, but is it generally accepted that having a belief implies the
use of language? Or do academics speak of linguistic beliefs and
non-linguistic beliefs?

Here is an extract that may help;
Beleif is a mental state, representational in character, taking a
proposition (either true or false) as its content and involved,
together with motivational factors, in the direction and control of
voluntary behaviour. (thinking; propositional attidtude;
representation). Belief (thought) is often (especially in the
philisophy of mind) taken to be the primary cognitive state; other
cognitive and conative states e.g. (knowledge, perception, memory,
intention ) being some combination of belief and other factors (such
as truth and justification in the case of knowledge). Beliefs involve
the deployment of Concepts: one cannot believe that something is a cow
unless one understands what a cow is and , in this sense, has the
concept cow (one neednt, of course understand the word "cow"). Once
can, to be sure, have beliefs about cows (these are called de re or
demonstrative beliefs) without knowing what a cow is.

So I suppose the answer is yes. One can have beliefs without language.
As I would hypothesise that a dog or a monkey probably understands
what a dog, monkey or cow is without being able to verbalise it. But I
suppose that this is at the crux of your question.

By the way the quoted passage comes from the The Oxford companion to philosphy.