The two tables are DATABASECHANGELOG and DATABASECHANGELOGLOCK. They are described in the documentation at https://www.liquibase.org/documentation/databasechangelog_table.html and https://www.liquibase.org/documentation/databasechangeloglock_table.html
It is possible to have them in a different schema in the database - see this forum thread https://forum.liquibase.org/topic/databasechangelog-table-in-seperate-schema-common-for-all-changes or this Stack Overflow entry: https://stackoverflow.com/questions/35031316/how-to-specify-schema-location-for-changelog-tables