A few tips on how to monitor status and performance of SQL services :
standard tools such as OS services, by verification of database access [1]
general performance parameters bound to OS, such as usage of processor, drive, RAM [2]
specialized performance parameters for SQL - performance countre [3]
measuring time of operations over the used database [4]
Links
[1] https://www.customermonitor.eu/how-cm-works-0/monitoring-and-diagnostics/availability-and-load-sql-servers/ms-sql-availability
[2] https://www.customermonitor.eu/how-cm-works-0/monitoring-and-diagnostics/availability-and-load-sql-servers/ms-sql-performance
[3] https://www.customermonitor.eu/how-cm-works-0/monitoring-and-diagnostics/availability-and-load-sql-servers/ms-sql-performance-0
[4] https://www.customermonitor.eu/how-cm-works-0/monitoring-and-diagnostics/availability-and-load-sql-servers/ms-sql-performance-1