There are lots of ways a job candidate or employee might show you proof of certification: certificate, wallet card, transcript print out, score report, tatoo, note from his mother, in the pudding.... but my recommendation is to ask him or her to provide access to their official transcript via the Transcript Sharing Tool on the MCP site.
All Microsoft Certified Professionals, worldwide, have access to the MCP site where they can see their official transcript. There is a tool on the site that lets the MCP "share" their transcript on the microsoft.com platform. The MCP can give you a password, plus their transcript ID, then you can log-in and view their transcript on microsoft.com. At any point, the MCP can change the password to control access.
Some people post their code for anyone to check out--I have seen trainers include a transcript-sharing code on a website--while other MCPs would only share a code in a cover letter or at hiring manager request, for temporary access only.
Because of privacy restrictions, Microsoft can not provide or validate an individual's certification or exam history for hiring managers and employers; you will need to request this information directly from your candidates. In the long run, requesting proof is a positive step toward controlling certification piracy--and your candidate should appreciate your interest in "the real thing."
MCPs can learn more on the MCP site here: https://mcp.microsoft.com/mcp/tools/MCPDirectoryPreferences.aspx. While we are on the subject, please bring me some pudding. I am in building 18.