Examples:

Images Courtesy of Wikimedia Commons:
Small Amplifier Circuit
Common Gate amplifier

                                    Fig. 1.  Small amplifier circuit. [1]

      Fig. 3.  Gate amplifier. (a) FET. (b) Resistor. (c) Capacitor. [4]

Place the Figure title/caption below the figure.

The caption number should be cited with the abbreviation “Fig.” then the number, followed by a period, an em space, and then by the caption text. 

The Figure, and Figure title/captions should be centre-justified.

When referring to multiple parts of figures: Use the singular Fig., not Figs. (e.g. Fig. 4(a) and 4(b)).

If you adapt or modify the figure, indicate this at the end of your caption.

Still unsure? Refer to the IEEE Editorial Manual for Authors on pages 12-13.

Examples:

Images courtesy of Pixabay and NASA:
Cell Tower
Bell X-5

                                Fig. 6.  Cell tower.

            Fig. 8.  Bell X-5 pitot tube. Adapted from [5]

Place the Image title/caption below the image.

If you adapt or modify the image, indicate this at the end of your caption.

Still unsure? Refer to the Preparation of Papers for IEEE TRANSACTIONS and JOURNALS on pages 3-5 and the IEEE Editorial Manual for Authors on pages 12-13.

Examples:

Note: This data is fictional and for demonstrative purposes only

TABLE IX

PARAMETERS

TABLE III

RESONANT FREQUENCY

Optimal frequency for oscillator testing with current field equipment. Adapted from [8]
^a 30 Hz was only detectable with a square wave test signal.
^b Note the 150 Hz comparison with a sine wave test signal.

Place the table title/caption above the table.

The Table, and Table title/captions should be centre-justified. Table title/captions should capitalised. TABLE should be enumerated with Roman numerals.

Vertical lines are optional. You can include explanatory notes below the table. Notes that apply to a specific part of the table can be marked like a footnote with superscript. Letters or numbers can be used. Statements that serve as captions for the entire table do not need footnote letters/numbers. 

​When referring to multiple parts of tables in text use the singular Table, not Tables. (e.g. Table. III¹) and III²)).

​If you adapt or modify the table, indicate this at the end of your caption.

Still unsure? Refer to the Preparation of Papers for IEEE TRANSACTIONS and JOURNALS on pages 3-5 and the IEEE Editorial Manual for Authors on pages 12-13.

For an in-print example using footnote numbers see:
M. de Freitas Junior, M. Fantinato and V. Sun, "Improvements to the Function Point Analysis Method: A Systematic Literature Review," IEEE Trans. Eng. Manag., vol. 62, no. 4, pp. 495-506, Nov. 2015, doi: 10.1109/TEM.2015.2453354.

TIP: IEEE also provides templates in Word and LaTeX for their publications. Visit their publication template selector here and choose an appropriate template:
https://journals.ieeeauthorcenter.ieee.org/create-your-ieee-journal-article/authoring-tools-and-templates/tools-for-ieee-authors/ieee-article-templates/