This is a great exercise that targets triceps while requiring only dumbbells
With many variations, the dips can be done with either weights or body weight to engage triceps and lower chest based on the grip.
The close-grip barbell press focuses primarily on the triceps with minimal load on the chest. It is a great exercise for building strength while isolating a muscle group as well.
Tricep cable pushdowns are an excellent isolation movement that lets you focus on upper arm and triceps for maximum growth and stimulation.