How to alter variable for ECK entity?

We are using the ECK module where we have created component eck_highlight (machine name). How would we be able to modify the variable array using a preprocess hook?

Eck_highlight component has this field:

• Field Reference to content types: basic, article, and event

Goal:

Call the preprocess to store 'info' array to vars (i.e. vars['info']). The info variable will be passed into the Twig template so we can use to output information.

mymodule_preprocess_eck_highlight(&$vars) { $vars['info'] += [ 'id' => 'some-id', 'height' => 'some-height', 'width' => 'some-width', 'src' => 'src1' ]; } 

We have tried to do the following but cannot alter the variables.

1. mymodule_preprocess_eck_highlight(&$vars)
2. mytheme_preprocess_eck_highlight(&$vars)