magento-module/etc/events.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <!-- Order create -->

    <event name="sales_order_save_after"> 
        <observer name="sales_order_save_after" instance="Retailcrm\Retailcrm\Model\Observer\OrderCreate" />
    </event>

    <!-- Order update -->

    <event name="sales_order_save_commit_after"> 
        <observer name="sales_order_save_commit_after" instance="Retailcrm\Retailcrm\Model\Observer\OrderUpdate" />
    </event>

    <!-- after customer save -->

    <event name="customer_save_after"> 
        <observer name="customer_save_after" instance="Retailcrm\Retailcrm\Model\Observer\Customer" />
    </event>
</config>