Explanation/Reference:
eDiscovery cases can be used in the Office 365 Security & Compliance Center to control who can create, access, and manage eDiscovery cases in your organization.
To set up and use eDiscovery cases in the Security & Compliance Center and Advanced eDiscovery, you can use the options below:
Step 1: Assign eDiscovery permissions to potential case members
Step 2: Create a new case
Step 3: Add members to a case
Step 4: Place content locations on hold
Step 5: Create and run a Content Search associated with a case
Step 6: Export the results of a Content Search associated with a case
Step 7: Prepare search results for Advanced eDiscovery
Step 8: Go to the case in Advanced eDiscovery
(Optional) Step 9: Close a case
(Optional) Step 10: Re-open a closed case
References: https://support.office.com/en-us/article/Manage-eDiscovery-cases-in-the-Office-365-Security- Compliance-Center-9a00b9ea-33fd-4772-8ea6-9d3c65e829e6