Symbolism can be a complicated addition to a story. Almost anything can be turned into a symbol. What the object chosen must have a meaning beyond itself. Symbolism often uses figures of speech to give the added meaning to the words.
A simile is a pairing of two words unlike each other. A smile hovered like a dark cloud. Makes the reader think this is not a friendly smile. Her smile burst like the sun rising. Here there's a different meaning to be inferred. This is kind of an in your face showing a hidden meaning.
A metaphor is another way of showing symbolism but a metaphor is more subtle. Metaphors are often images thet lead one to another. The dress hung from her body. He thought of a tattered flag bringing to mind a ship tossed by a hurricane.
So a symbol can have many meaningsby forming associations with other words.
I've often used both in my stories when I want to create a vivid feature. Once I searched through my stories and found many similes and then came upon items I used as metaphors. Caves were one and gems another.
So do you use these techniques and realize you are creating symbols without really thinking about them?