It is important to note that in addition to other conditions, financial ability to bear all travel expenses and complete ability to perform Hajj are also key requirements for Hajj to become obligatory. Otherwise, Hajj is not obligatory.
Therefore, simply performing Umrah will not make Hajj obligatory. However, if a person who has not performed his Farz Hajj before goes for Umrah in the months of Hajj (Shawwal, Dhu al-Qadah, and the first ten days of Dhu al-Hijjah), then Hajj will become Farz for them only if they meet certain conditions. These conditions include having legal authorization to stay there until Hajj and either being able to afford the expenses of Hajj until that time, or having sufficient financial means to return and perform Hajj later on. If these conditions are not met, then Hajj will not be obligatory for them.