How to call module in component?

Modules can be placed anywhere on the page, including component page. You can specify the position in module settings. And if you meant how to place a module inside contents then you can use {loadposition position} directive.
You can call module by its position like this any where in the code like “components/modules”

$modules =& JModuleHelper::getModules(‘breadcrumb’);
foreach ($modules as $module)
{
echo JModuleHelper::renderModule($module);
}

Here “breadcrumb” is the module position you can use .